(I have also tried to set only case insesitively and not accent insensitively using BINARY_CI, but with no good effect).

If I have the same text in a varchar2 column, I can do the case and accent insensitive search, but not in the clob column because it returns the records only if they contain the exact match in that clob column.

The reason I hope there is a way of avoiding to use Oracle Text is that the syntax I need to use is too specific to Oracle and I don't even know how easy would be to use it with the ORM I use.